Tennis stroke practice device



lJune 24, 194i. T. D. STOW TENNIS STROKE PRACTICE DEVICE Filed Feb. 5,1940 ,ma 8 N 2 6 IN V EN TOR.

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' BYH ATTORNEY Patented June 24, 1941 UNITED STATES PATENT oFFicE TENNISSTROKE PRACTICE DEVICE Thomas D. Stow, Berkeley, Calif.

Application February 5, 1940, Serial No. 317,344

8 Claims.

This invention relates to practice devices for the development of tennistechnique, and has for its principal object such a device which will besimple and effective for the purpose, adaptable for short, medium, andtall pupils, and for every type of stroke, and such a device in whichobjectionable back and forth oscillations of the ball after hitting islargely dampened out, so that another stroke may be taken at the ballalmost immediately after a heavy drive. Other objects and advantages ofthe invention will appear in the following description and accompanyingdrawing.

In the drawing:

Fig. 1 is a perspective View showing my improved tennis stroke practicedevice mounted on the side wall of a building for use.

Fig. 2 is a cross section of the practice tennis ball showing the meansemployed for mounting it on the rubber cord. Y

Fig. 3 is a longitudinal section of the oscillation dampener.

Fig. 4 is an enlarged perspective view showing the arm supportingbracket and detachable arm.

Briefly described the device includes a suspending b-racket I forattaching to the side of a post or building 2 at an elevated positionand suspending two practice tennis balls 3 and 4 on elastic cords 5, 6in such a manner as to accommodate drives, or `volleys on one ball andoverhead strokes, serves, and smashes on the other, both balls beingadjustable along their elastic cords to suit the height of theparticular player or the type of stroke being practiced, and the drivingVpractice ball particularly being provided with oscillation dampeningmeans 'I so that even after a hard driving stroke the ball will almostat once quiet down for another stroke.

In the drawing the bracket I is shown as a hollow, horizontallyprojecting socket member having a wall plate B with holes 9 for boltingto a wall or post, and the socket member is formed to receive adetachable arm Ill carrying a projecting threadedV stud Il which slidesinto a groove I2 in the socket, and is secured in place by a wing nutI3.

Rigidly secured to the under side of the socket or arm is a largeeyebolt or screw eye I4, and at the end of the arm is another similareyebolt or screw eye I5, and at about an equal ldistance from eyebolt I4measured downwardly along the wall 2 is another screw eye or eyebolt I6.Elastic cord passes through ball 3 and the three eyelets in the form ofa triangle and has its ends tied or otherwise secured together as at 5in a manner to bring the knot against the wall 2.

Also passing through eyes I5, and I4 and fixedly tied or secured at oneend to eye IB as at I'I is a cord or rope I1 tied at its other end as atI8 to the upper end of elastic cord 6 which passes vertically downwardthrough ball 4 and is secured at 6 to an eyelet I9 at the upper end of adumbbell-like device 20 which hangs freely in a slot 2l between a pairof spaced bars 22 formed with upright legs 23 secured to a shoe 24 ateach end in turn secured to a base plate 25 which lies upon the groundand may be of wood, or of metal to give it weight, or be spiked in placeif desired, though this is generally unnecessary. The legs 23 arepreferably tied together at the upper ends as by small plates 26 and theheight of the legs is such as to permit the dumbbell 20 to always swingclear of the plate 25. This may be assured by adjusting the knot Il.`The slot 2l extends parallel to the wall 2 from which the bracket armI0 projects at right angles.

The dampener member or dumbbell-like device 2ll is preferably of rubberand with the balls 2| at its ends made of a good tough grade of spongerubber and the assemblage is held together by` a light rod I9 passingthrough, the upper end of which rod is formed with the eyelet I9 'andthe lower end is threaded and fitte-d with a wing nut 2l.

The elastic cords 5 and 6 are preferably made of a large number ofelastic rubber strands 28 enclosed in a suitable woven cover on thenature of the enclosures of a flexible electric cord, and the'balls 3and 4 are adjustably held in place in the manner shown in Fig. 2 wherein29 is a tube, preferably of ylirm rubber (though it may be of metal orother material) passing through the ball 4 and projecting at both endsand surrounded by a pair of washers 30, which are preferably'of rubberand cemented in place or they may be nuts screwed on tube 29 if thelatter be of metal, or plastic. Within the rubber tube 29 is a softrubber tube 3| which projects somewhat beyond tube 29 and is preferablyheld in place by a slight coating of rubber cement pressed upon it atthe time it was inserted in the outer tube 29. The bore or holeextending through the inner rubber tube 3| is of a size somewhat smallerthan the normal diameter of the elastic cord 6 so that the elastic cordis cornpressed to smaller diameter over that portion of it embraced bythe tube 3l and immediately expands toits normal size at both ends ofthe l tube as indicated in Fig. 2. By this means the balls 3 and 4 willnever become displaced on their elastic cords and 6 no matter how hard ablow is given them with the racket. In order to shift either ball up ordown on its elastic cord, it suicesto stretch the cord with the hands onboth sides of the ball so as to reduce its diameter, and at which timethe ball may be slid along the thus reduced diameter to any pointdesired and when the elastic cord is relaxed again it will swell up atopposite ends of tube 3| to firmly lock the ball in place as previouslydescribed, and indicated in Fig. 2. Ball 3 may also be adjusted byshifting cord 5 through the eyelets. Since the joints between the balland the tube may be made air tight with cement, gas under pressure maybe introduced into the ball if desired, though I have not found itnecessary.

From the above description the operation of the device is thoughtobvious, as it is evident to any tennis player that ball 4 may be usedfor any type of ground or drive stroke, and ball 3 for any overhead,smash or serving stroke, so that between these twol balls variouslyadjusted along their respective `elastic cords 5 and 6 as may berequired, everypossible tennis stroke may be j practiced, and owing tothe particular arrangement shown by the assemblage 1 the loosedumbbell-like device hanging pendulously in loose limited guides 22,together with the nature of the pendulous body and its sponge rubberballs 2| at Vopposite ends, the motion given ball 4 by even the mostpowerful blow is dampened Within a; few moments, as the oscillationscannot berhythmic and are very rapidly brought to a stop; It is needlessto say that the same `dampening arrangement may be applied to ball 3 Vifdesired but as ball 3 is not used as often as ball l in ipractice work,it is not so important. I

Byhaving arm IU detachable and at least eyes I4' and I 6 open at oneside as indicated in the drawing, the arm together with the elasticcords, balls, and dampeningdevices may be taken indoors during inclementweather and the arm I0 inserted in a `duplicate socket I mounted withina building or in some protected spot, soV that the apparatus maybealmost instantly erected in either place. It being understood that aduplicate eyelet I6 is also left permanently in the in-Y door positionas well as in the outdoor position.

I liavetriedother means of dampening the oscillations of ball 4, andfind 'it can only be done by avoiding a iixedconnection at the lowerendfof the 'flexible cord 6, as such a connection permits of 4agradually decreasing rhythmic vibration to the ba1l`after once beingstruck, whereas by suspending some loose object which is capable of amore or less limited motion, the rhythm is broken in such a manner thatthe ball comesquickly to`rest.' After experiments with variousV forms ofrhythm disturbing elements, I found the, dumbbell-like device shown tobe very satisfactory, and at the same time to be free` from noise aslits construction of sponge rubber absorbs the shock and sound, and alsoadds no disturbing weight which might aect the value of the stroke.Instead of rubber, felt or other soft tough material may be used.

Having thus described my improved tennis practice device and the mannerof its use it will be evident that modifications may be made within thespirit of the invention and as may fall within the scope of the appendedclaims.

I claim:

1. In a tennis practice device, a ballY supported on an elastic cord ina manner adapted for striking by a player, and means depending from theelastic cord for dampening ,the oscillations of the ball when struck,said means including a pendulous body and retainer means formed with aslot embracing said body and extending substantially parallel to thedirection of the stroke for limiting the motion of said body.

2. In the construction as set out in claim 1 said pendulous body beingof elongated form with soft resilient exterior surface and enlarged atthe ends.

3. In the construction as set out in claim 1 said pendulous body beingof elongated form With rubber-like balls at its ends.

4. In the construction as set out in claim 1 said pendulous body beingof elongated form with spronge rubber balls at its ends.

5. In a tennis practice device, a ball, an elastic cord passing throughand for suspending said ball, and a soft rubber tube extending throughsaid ball and surrounding said elastic cord and compressing said cordwhere it passes through the ball to retain the ball in any desired pointof adjustment along said elastic cord and an outer relatively rigid tubeenclosing said soft rubber tube.

6. In a structure as set out in claim 5, the relatively rigid tubesurrounding said rubber tube projecting beyond opposite sides of theball and a washer secured in place around each projecting end in contactwith the ball.

7. In a tennis practice device, an elastic cord, means supporting thecord in upward extension, a ball supported at an intermediate point onsaid elastic cord in a manner adapted for striking by a player, andmeans depending from the lower end of said elastic cord for dampeningthe oscillations of the ball when struck, said means including apendulous body interfering with rhythmic swinging motion of said ballwhen struck.

8. In a tennis practice device, an elastic cord, means supporting thecord in upward extension, a ball supported at an intermediate point onsaid elastic cord in a manner adaptedfor striking by a player, and meansdepending from the lower end of said elastic cord for dampening theoscillations of the ball when struck, said means including a pendulousbody and retainer means formed with a guide limiting the motion of saidbody and thereby interfering with the rhythmic swinging motion of saidball when struck.

THOMAS D. STOW.

